It's widely believed that men are more successful than women because there are more male geniuses than female geniuses. However, Richard Feynman has an IQ of only 126, and James_Watson has an IQ of only 115. Why are they very successful dispite their low IQs? Aren't men supposed to be more intelligent than women?
There's a study that testosterone increases status-seeking behavior. This study may suggest that males succeed not because of their intelligence, but because of their ambition.
There may be many women who are geniuses, but these women don't have the motivation to use their intelligence to become successful. Genius may be a product of ambition, rather than intelligence.
It's sad to realize that the testosterone levels of both sexes are falling, and humanity in general is becoming less and less ambitious.
I have some hypotheses of why there are more male idiots than female idiots:
- Females have two X chromosomes, so the X chromosomes have protective effects against each others. In contrast, males have only one X chromosome. So males don't have the protective effect of two X chromosomes, thus men may have a greater chance of being an idiot.
- Men are more risk-taking. So men are more prone to do activities which result in brain trauma, thus producing more idiots.
- Men are more independent than women. Men are less submissive and more tolerant to conflict than women. So a greater proportion of men might not care about scoring high on IQ tests as women do.
Typical IQ tests measure a person's pattern matching and pattern recognition abilities. So IQ tests are skewed towards spatial intelligence. In fact, men have much better spatial intelligence than women. So this explains why men score higher on IQ tests than women.
Spatial intelligence is correlated with logical-mathematical intelligence. People who are good on IQ tests would also have good mathematical skills.
There are also differences in spatial intelligence between the races. For example, there's a stereotype that Asians, who have good spatial abilities, are good at mathematics.
Surviving in cold climates require more spatial intelligence than surviving in the tropics. In the tropics, there are plenty of fruits and tubers to eat all year around. However, in cold climates, these plant's aren't as abundant, so humans who live in a colder climate must hunt more animals.
Spatial intelligence is required for hunting skills. Navigating the terrain, estimating how far an object is, identifying animal tracks, and estimating the speed of a moving object, are spatial skills; which are vital for hunting animals.
Asians evolved from very cold climates. East Asians on average have higher spatial intelligence than whites; about one standard deviation higher.
Also, men have visual-spatial intelligence about one standard deviation higher than women, which is the result of natural selection during the hunter-gatherer society.
Spatial Intelligence and Mathematical Ability
Spatial intelligence is highly correlated with logical-mathematical intelligence. The higher the visual-spatial intelligence, the better the math skills. Solving a math problem requires the human mind to imagine and manipulate symbols in their visual memory. Mathematical symbols, such as numbers, must be visualized and manipulated in the human brain. The higher the visual-spatial intelligence, the faster you solve a math problem. This is faster because you can visually calculate in your head instead of solving the problem on paper or using the limited and slower short-term memory.
IQ Tests are Biased
Intelligent quotient (IQ) tests, which have time limits, are related to math skills and symbolic manipulation skills. The faster you will solve the pattern in an IQ test, the more problems get done, and the higher score you will get. High spatial intelligence is advantageous in IQ tests since problems can be quickly visually solved in the mind, instead of using the slower and limited short-term memory. Without a high visual-spatial intelligence, you cannot manipulate the symbols as easy, and will manipulate them slower, then getting a lower score on a IQ test.
There are no significant differences in "general intelligence" between the races if and only if "general intelligence" doesn't take account of spatial intelligence. However, the general intelligence factor, especially testing among the Raven's Progressive Matrices, is strongly correlated with spatial intelligence.
Spatial Intelligence confused with "General Intelligence"
I don't believe in "general intelligence." But let me explain why people confuse these two things.
The reason that Ashkenavi Jews score high on IQ tests is not because of their spatial intelligence, since theirs is low. But we do conjecture that Jews possess a high short-term auditory memory. The reason that they score high on IQ tests is not visual-spatial intelligence such as Asians do, but their short-term memory. Evidence: They have good verbal intelligence, which may be an effect of their short-term memory. Information must be articulated in short-term memory to retain. John von Neumann, a Jew, is able to recite thousands of digits after memorizing them in a few minutes. (But do they are able to recite the digits backwards? Reciting backwards is much harder, since it apparently requires an extraordinarily amount of visual-spatial memory, which Ashkenazi Jews Lack. They need visual-spatial memory to represent the digits so they can recite digits backward efficiently (read the digits backward in the visuospatial sketchpad). Therefore, we hypothesize that Asians are better in reciting digits backwards.) He also has fast mental calculation.
Some evidence supports this hypothesis. Jews have a much more incidence of diseases like Tay-Sachs. People with Tay-Sachs have improved brain function.
Some sources (reliable or not) suggest that Asians have lower processing speed than "whites" (or mistakenly Ashkenazi Jews, since Jews are often mistaken to whites). If these "whites" are actually Jews, then we believe that these Jews have much higher and faster short-term memory than Asians. It says that Jews have faster processing speed (mental calculation) than Asians. Short term memory is better than visuospatial memory for mental calculation, since it is a more efficient representation than visuospatial. We believe that is because Jews must have high short-term memory to compensate the visuospatial memory of Asians to succeed at IQ tests. More short-term memory manipulations are required to solve an IQ problem than the number of visualspatial manipulations. Therefore, Jews must have a MUCH higher short-term memory to exceed Asians. Since short-term memory is more efficient in mental processing than IQ tests, that is why Jews has faster mental processing time.
East Asians score high on the visualspatial sections of the IQ test. Jews score extremely high on the verbal sections (short term memory) of the IQ test.
For example, the Black-White gap is larger on tests that require the recall of a series of digits in reverse order than on tests that require the recall of a series of digits in forward order. Across a large number of test, the standardized mean Black-White gap varies from near zero to over one standard deviation. According to Jensen 1998b, "this variation between tests in the size of the standardized mean W-B difference is not explainable in terms of test bias or in terms of differences in types of item content or other formal or superficial characteristics of the tests."
For example, the Black-White gap is greater on backward digits span (a test where subjects repeat digits in the reverse order that they are given, and the more g-loaded test) than forward digits span (a test where subjects repeat digits in the same order that they are given, and the less g-loaded test). As predicted by Spearman's hypothesis, the B-W gap is largest on the most g-loaded tests. Narrowing of the B-W gap has been seen mostly on less g-loaded tests, such as literacy tests.
The gap is larger to recall digits in reverse because blacks are much lower in visual intelligence.
"a test where subjects repeat digits in the reverse order that they are given, and the more g-loaded test"
IQ tests, and specifically "g-loaded" tests, are biased against blacks because they are designed to test people with high visualspatial intelligence, which blacks are relatively low at.
This is also supported by the study that IQ tests are biased in favor males because IQ tests measure spatial intelligence, which men excel at. 
IQ Testing is Flawed
Some racist scientists would trust studies which conclude that Africans have an average IQ of 70. This is flawed because most Africans are illiterate and most of them don't know how to take the test. In addition, most Africans live in an impoverished environment and have experienced fluoride poisoning, heavy metal poisoning, iodine deficiency, vitamin A deficiency, vitamin K2 deficiency, and many other stressors which lower their average IQ.
There are plenty of examples of testing bias when done to African children. At the first attempt the African children scored an average of 70 on the IQ test. However, after the instructors taught the children how to do these tests, the children improved their score to 85.
Yes, the above hypotheses makes me sound like a racist to some, but I have argued otherwise. I have argued that IQ tests are biased against black people. I have used the research from the racist scientists to argue against these scientists themselves.
And, please, don't assume that I believe that men, on average, are "more intelligent" than women. Like I mentioned at the top of the article, the reason that almost all successful people are men but not women has nothing to do with their intelligence. It's because men are more status-seeking than women are.
 Rushton, J (2000) Richard Race, Evolution and behavior
 Murray, C. (2005) The Inequality Taboo. Commentary Magazine, September 2005.
 Abad, F. et al (2002) Sex differential item functioning in the Raven’s Advanced Progressive Matrices: evidence for bias. School of Psychology, Autonomous University of Madrid